#!/usr/bin/env python

# verify.py                                          Version 0.1      2009-10-18
#
# under the WTFPL. see http://sam.zoy.org/wtfpl/
#
#             DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE 
#                     Version 2, December 2004 
# 
#  Copyright (C) 2006 solsTiCe d'Hiver               <solstice.dhiver@gmail.com>
#  Everyone is permitted to copy and distribute verbatim or modified 
#  copies of this license document, and changing it is allowed as long 
#  as the name is changed. 
# 
#             DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE 
#    TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 
# 
#   0. You just DO WHAT THE FUCK YOU WANT TO.

'''a python script that compare the files in a package tarball and the files
installed on the system:
    It reports changed files, missing files'''

import tarfile
import hashlib
from sys import argv, exit, stderr, stdin
from os import listdir
from os.path import exists, basename
from glob import glob

DB = '/var/lib/pacman'
CACHE = '/var/cache/pacman/pkg'

# TODO: use logging module ?
def error(s):
    stderr.write('Error: %s\n' % s)

def warning(s):
    stderr.write('Warning: %s\n' % s)

def getpkgname(pkgfile):
    '''return package name from its pkgfilename'''
    pkg = basename(pkgfile.rstrip('.pkg.tar.gz'))
    pkg = pkg[:pkg.rfind('-')]
    return pkg

def ispkginstalled(pkgfile):
    '''return wether or not a package is installed'''
    return exists('/'.join([DB, 'local', getpkgname(pkgfile)]))

def checkpkg(pkgfile):
    '''check if the installed files of a package have changed compared to the
    files in the package tarball'''
    missing = 0
    changed = 0
    md5s = md5pkg(pkgfile)
    for filename,md5 in md5s.items():
        ff = '/' + filename
        if exists(ff):
            try:
                with open(ff) as g:
                    if hashlib.md5(g.read()).hexdigest() != md5:
                        warning('%s has changed' % ff)
                        changed += 1
            except IOError as e:
                error('%s: %s ' % (e.strerror, filename))
                continue
        else:
            warning('%s has not been found' % ff)
            missing += 1
    return (len(md5s), changed, missing)

def listpkg():
    '''return a list of all isntalled pkg'''
    return sorted(listdir('/'.join([DB, 'local'])))

def findpkg(s, dbpkg):
    '''look for an installed pkg matching s and return the path of tarball in
    the cache'''
    candidates = [p for p in dbpkg if p.startswith(s)]
    found = False
    for i in candidates:
        pkgname = '-'.join(i.split('-')[:-2])
        if pkgname == s:
            found = True
            break
    if found:
        res = glob('/'.join([CACHE, i+'*']))
        if len(res) == 1:
            return res[0]
    return None

def md5pkg(pkgfile):
    '''return a dictionary of filename and md5 of the package'''
    tf = tarfile.open(pkgfile, 'r')
    md5s = {}
    for ti in tf:
        if ti.isfile() and ti.name not in ('.PKGINFO', '.INSTALL', '.CHANGELOG'):
            f = tf.extractfile(ti)
            md5s[ti.name] = hashlib.md5(f.read()).hexdigest()
            f.close()
    tf.close()
    return md5s

if __name__ == '__main__':
    dbpkg = listpkg()
    try:
        if len(argv) == 1:
            # try to use stdin if no argument
            pkglist = stdin.readlines()
            pkglist = [i.strip() for i in pkglist]
        else:
            pkglist = argv[1:]
        for pkg in pkglist:
            if exists(pkg):
                if not ispkginstalled(pkg):
                    error('%s is not installed' % getpkgname(pkg))
                    continue
            else:
                # if we do not find the archive pkg, then look for a package with
                # that name in the db of pacman
                p = findpkg(pkg, dbpkg)
                if p != None:
                    # strange but it works
                    pkg = p
                else:
                    error('%s not found' % pkg)
                    continue
            # finaly check the tarball pkg
            (n,c,m) = checkpkg(pkg)
            print '%s: %d files, %d changed, %d missing' % (getpkgname(pkg), n, c, m)
    except KeyboardInterrupt:
        pass